📄 calendar.html
字号:
be 31 in the month April. Add rule 2 sets it to the closest possible value, 30. Finally, the <strong>roll rule</strong> maintains the <code>YEAR</code> field value of 1999.</p> <p><em>Example</em>: Consider a <code>GregorianCalendar</code> originally set to Sunday June 6, 1999. Calling <code>roll(Calendar.WEEK_OF_MONTH, -1)</code> sets the calendar to Tuesday June 1, 1999, whereas calling <code>add(Calendar.WEEK_OF_MONTH, -1)</code> sets the calendar to Sunday May 30, 1999. This is because the roll rule imposes an additional constraint: The <code>MONTH</code> must not change when the <code>WEEK_OF_MONTH</code> is rolled. Taken together with add rule 1, the resultant date must be between Tuesday June 1 and Saturday June 5. According to add rule 2, the <code>DAY_OF_WEEK</code>, an invariant when changing the <code>WEEK_OF_MONTH</code>, is set to Tuesday, the closest possible value to Sunday (where Sunday is the first day of the week).</p> <p><strong>Usage model</strong>. To motivate the behavior of <code>add()</code> and <code>roll()</code>, consider a user interface component with increment and decrement buttons for the month, day, and year, and an underlying <code>GregorianCalendar</code>. If the interface reads January 31, 1999 and the user presses the month increment button, what should it read? If the underlying implementation uses <code>set()</code>, it might read March 3, 1999. A better result would be February 28, 1999. Furthermore, if the user presses the month increment button again, it should read March 31, 1999, not March 28, 1999. By saving the original date and using either <code>add()</code> or <code>roll()</code>, depending on whether larger fields should be affected, the user interface can behave as most users will intuitively expect.</p><P><DL><DT><B>Since: </B><DD>JDK1.1</DD><DT><B>See Also: </B><DD><A HREF="../../java/util/Date.html"><CODE>Date</CODE></A>, <A HREF="../../java/util/GregorianCalendar.html"><CODE>GregorianCalendar</CODE></A>, <A HREF="../../java/util/TimeZone.html"><CODE>TimeZone</CODE></A>, <A HREF="../../java/text/DateFormat.html"><CODE>DateFormat</CODE></A>, <A HREF="../../serialized-form.html#java.util.Calendar">Serialized Form</A></DL><HR><P><!-- ======== INNER CLASS SUMMARY ======== --><!-- =========== FIELD SUMMARY =========== --><A NAME="field_summary"><!-- --></A><TABLE BORDER="1" CELLPADDING="3" CELLSPACING="0" WIDTH="100%"><TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor"><TD COLSPAN=2><FONT SIZE="+2"><B>Field Summary</B></FONT></TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>static int</CODE></FONT></TD><TD><CODE><B><A HREF="../../java/util/Calendar.html#AM">AM</A></B></CODE><BR> Value of the <code>AM_PM</code> field indicating the period of the day from midnight to just before noon.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>static int</CODE></FONT></TD><TD><CODE><B><A HREF="../../java/util/Calendar.html#AM_PM">AM_PM</A></B></CODE><BR> Field number for <code>get</code> and <code>set</code> indicating whether the <code>HOUR</code> is before or after noon.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>static int</CODE></FONT></TD><TD><CODE><B><A HREF="../../java/util/Calendar.html#APRIL">APRIL</A></B></CODE><BR> Value of the <code>MONTH</code> field indicating the fourth month of the year.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>protected boolean</CODE></FONT></TD><TD><CODE><B><A HREF="../../java/util/Calendar.html#areFieldsSet">areFieldsSet</A></B></CODE><BR> True if <code>fields[]</code> are in sync with the currently set time.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>static int</CODE></FONT></TD><TD><CODE><B><A HREF="../../java/util/Calendar.html#AUGUST">AUGUST</A></B></CODE><BR> Value of the <code>MONTH</code> field indicating the eighth month of the year.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>static int</CODE></FONT></TD><TD><CODE><B><A HREF="../../java/util/Calendar.html#DATE">DATE</A></B></CODE><BR> Field number for <code>get</code> and <code>set</code> indicating the day of the month.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>static int</CODE></FONT></TD><TD><CODE><B><A HREF="../../java/util/Calendar.html#DAY_OF_MONTH">DAY_OF_MONTH</A></B></CODE><BR> Field number for <code>get</code> and <code>set</code> indicating the day of the month.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>static int</CODE></FONT></TD><TD><CODE><B><A HREF="../../java/util/Calendar.html#DAY_OF_WEEK">DAY_OF_WEEK</A></B></CODE><BR> Field number for <code>get</code> and <code>set</code> indicating the day of the week.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>static int</CODE></FONT></TD><TD><CODE><B><A HREF="../../java/util/Calendar.html#DAY_OF_WEEK_IN_MONTH">DAY_OF_WEEK_IN_MONTH</A></B></CODE><BR> Field number for <code>get</code> and <code>set</code> indicating the ordinal number of the day of the week within the current month.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>static int</CODE></FONT></TD><TD><CODE><B><A HREF="../../java/util/Calendar.html#DAY_OF_YEAR">DAY_OF_YEAR</A></B></CODE><BR> Field number for <code>get</code> and <code>set</code> indicating the day number within the current year.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>static int</CODE></FONT></TD><TD><CODE><B><A HREF="../../java/util/Calendar.html#DECEMBER">DECEMBER</A></B></CODE><BR> Value of the <code>MONTH</code> field indicating the twelfth month of the year.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>static int</CODE></FONT></TD><TD><CODE><B><A HREF="../../java/util/Calendar.html#DST_OFFSET">DST_OFFSET</A></B></CODE><BR> Field number for <code>get</code> and <code>set</code> indicating the daylight savings offset in milliseconds.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>static int</CODE></FONT></TD><TD><CODE><B><A HREF="../../java/util/Calendar.html#ERA">ERA</A></B></CODE><BR> Field number for <code>get</code> and <code>set</code> indicating the era, e.g., AD or BC in the Julian calendar.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>static int</CODE></FONT></TD><TD><CODE><B><A HREF="../../java/util/Calendar.html#FEBRUARY">FEBRUARY</A></B></CODE><BR> Value of the <code>MONTH</code> field indicating the second month of the year.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>static int</CODE></FONT></TD><TD><CODE><B><A HREF="../../java/util/Calendar.html#FIELD_COUNT">FIELD_COUNT</A></B></CODE><BR> The number of distict fields recognized by <code>get</code> and <code>set</code>.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>protected int[]</CODE></FONT></TD><TD><CODE><B><A HREF="../../java/util/Calendar.html#fields">fields</A></B></CODE><BR> The field values for the currently set time for this calendar.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>static int</CODE></FONT></TD><TD><CODE><B><A HREF="../../java/util/Calendar.html#FRIDAY">FRIDAY</A></B></CODE><BR> Value of the <code>DAY_OF_WEEK</code> field indicating Friday.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>static int</CODE></FONT></TD><TD><CODE><B><A HREF="../../java/util/Calendar.html#HOUR">HOUR</A></B></CODE><BR> Field number for <code>get</code> and <code>set</code> indicating the hour of the morning or afternoon.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>static int</CODE></FONT></TD><TD><CODE><B><A HREF="../../java/util/Calendar.html#HOUR_OF_DAY">HOUR_OF_DAY</A></B></CODE><BR> Field number for <code>get</code> and <code>set</code> indicating the hour of the day.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>protected boolean[]</CODE></FONT></TD><TD><CODE><B><A HREF="../../java/util/Calendar.html#isSet">isSet</A></B></CODE><BR> The flags which tell if a specified time field for the calendar is set.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>protected boolean</CODE></FONT></TD><TD><CODE><B><A HREF="../../java/util/Calendar.html#isTimeSet">isTimeSet</A></B></CODE><BR> True if then the value of <code>time</code> is valid.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>static int</CODE></FONT></TD><TD><CODE><B><A HREF="../../java/util/Calendar.html#JANUARY">JANUARY</A></B></CODE><BR> Value of the <code>MONTH</code> field indicating the first month of the year.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>static int</CODE></FONT></TD><TD><CODE><B><A HREF="../../java/util/Calendar.html#JULY">JULY</A></B></CODE><BR> Value of the <code>MONTH</code> field indicating the seventh month of the year.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>static int</CODE></FONT></TD><TD><CODE><B><A HREF="../../java/util/Calendar.html#JUNE">JUNE</A></B></CODE><BR> Value of the <code>MONTH</code> field indicating the sixth month of the year.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>static int</CODE></FONT></TD><TD><CODE><B><A HREF="../../java/util/Calendar.html#MARCH">MARCH</A></B></CODE><BR> Value of the <code>MONTH</code> field indicating the third month of the year.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>static int</CODE></FONT></TD><TD><CODE><B><A HREF="../../java/util/Calendar.html#MAY">MAY</A></B></CODE><BR> Value of the <code>MONTH</code> field indicating the fifth month of the year.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>static int</CODE></FONT></TD><TD><CODE><B><A HREF="../../java/util/Calendar.html#MILLISECOND">MILLISECOND</A></B></CODE><BR> Field number for <code>get</code> and <code>set</code> indicating the millisecond within the second.</TD>⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -